Currently, users may apply for a digital certificate from a certificate authority and may present government-issued credentials, among other forms of identification to the certificate authority for user verification. The certificate authority will issue a digital certificate to the user when verified. The digital certificate will be signed with the CA's private key. External CAs register their public key with major browser-makers such as Apple (Safari), Google (Chrome), Netscape (Firefox), and Microsoft (Internet Explorer). When a user presents her certificate to a browser-accessed application, the browser may use the CA's public key to check whether the user's certificate is valid.
Digital certificates are used in blockchain identity systems such as Netki, which issues digital certificates for the blockchain and uses blockchain Payment Protocol (BIP70/75).
Blockchains are useful for immutably recording digital assets for users. However, user identities may or may not have been verified.